PROBLEM
In the process planning instead of an end date, a time is displayed.
SOLUTION
The imported mpp file was scheduled on an hourly basis instead of a daily basis (duration is specified in hours h). Therefore, the end date of the process is replaced by the respective start time.
To avoid this, the process planning would have to be exported to a mpp file and there the planning would have to be adjusted from hours to days.
If you then import the file again, then the start and end date will also be displayed again.